1. Field of the Invention
The present invention relates to image reading apparatuses such as electrophotographic printers and copying machines.
2. Description of the Related Art
Electrophotography is typically used in many image forming apparatuses, and includes essential steps of charging, exposing, developing, transferring and fixing. A charging unit uniformly charges the surface of an image bearing body. An exposing unit illuminates the charged surface of the image bearing body to form an electrostatic latent image. A print engine supplies a developer material to the electrostatic latent image to form a developer image. A transfer unit transfers the developer image onto a recording medium.
Deterioration of the developer material causes deterioration of printed images. For this reason, some conventional apparatuses are configured to discard the deteriorated developer material from the developer bearing body to the image bearing body and then to the outside of the image forming apparatus. JP2004-125829 discloses one such apparatus.
However, JP2004-125829 is configured to discard the deteriorated developer material when the process cartridge 100 operates in all environments including an environment in which images are not likely to deteriorate. This implies that the developer material may have been discarded more than necessary.